Nick Kyrgios withdrew from the inaugural edition of the United Cup due to an injury he sustained while playing exhibition tennis in Dubai at the World Tennis League.
Kyrgisos withdrew only 24 hours before the start of the event indicating that he was holding out hope of being able to play but ultimately he elected against it due to the proximity of the Australian Open. That is one of the most important events of the year for him so risking that would be unwise.
The news came out on social media with a post that reads:
"Nick Kyrgios has withdrawn from the United Cup due to injury. Alex de Minaur will move into the No.1 men’s position for Team Australia, and subsequently Jason Kubler moves into the No.2 spot".
Team Captain Sam Stosur briefly commented on it:
“We literally just found out 10 minutes ago."